Musnad Ahmad 33:880

Azhar ibn al-Qasim al-Rasibi narrated to us in Makkah, and Kathir ibn Hisham, they both said: Hisham narrated to us, from Abu al-Zubayr, from Jabir, who said: "The Messenger of Allah, peace and blessings of Allah be upon him, forbade the selling of date palms until they have produced fruit."